Measurements of physical-chemical parameters in the field
Physico-chemical parameters [temperature, conductivity, concentration of dissolved solids, salinity, dissolved oxygen concentration (mg/l), oxygen saturation (%), pH, turbidity] are measured with portable sensors (picture 1) in different depths and three locations according to the hydro-morphological conditions. The equipment used for the above parameters is the AQUAREED (AM200, AP2000 + turbidity sensor) with the following specifications (table 1):
Picture 1: Portable AQUAREED (AM200, AP2000 + turbidity sensor)
Table 1. Physico-chemical measurement specifications
BOD5 estimation
The determination of biochemical oxygen demand (BOD5) (collected in a glass flask of 250ml) is calculated as the difference of the oxygen concentration in water measured initially and five days later; duringthese days the flask is maintained airtight and darkroom at 20 ° C (5210 B, APHA 1985).
Ion nutrient analysis in the field
Filtered water (through WHATMAN 0,45mm filters) is used for the measurement of nutrient ions (N-NO3, N-NO2, N-NH4 and P-PO4) with the portable photometer of MERC Company (picture 2) (model: AQUA NOVA 60A) containing:
• A rechargeable battery,
• Visible spectrum filters with diode technology arranged in order to eliminate cell error, including standard curves,
• At least 12 filters with diode technology arranged(half-width optical beam ≤ 10 nm, Photometric repeatability: ± 0.001 D = 1.000, Photometric analysis : 0.001 A),
• Ability to measure concentration, absorption, color and kinetic,
• Automatic recognition "barcode" (for rectangular cells and test tubes),
• Capability to use cells (10mm, 20mm, 50mm and 16mm diameter) with automatic recognition (not necessitating the use of receptors),
• Automatic turbidity correction,
• Data transfer to computer,
• Ensures the quality analysis assurance: controlling the instrument and the whole system by means of the VIS standards and multiparameter standards in line with the VIS standards and controlling the sample influence by means of Matrix Check operation.
Picture 2. Portable photometer of MERC Company (model: AQUA NOVA 60A) for nutrient ion analysis.
If the first measurement is out of range due to the selected method kit, there is the option to measure again using another set of different concentrations.
The nutrient concentrations are analyzed based on the limits of Table 2. When there is a sample that it is not possible to be analyzed with the portable instrument in the field, then it is transfered for analysis to the laboratory according to the Standard Methods for Examination of water and wastewater (A.P.H.A., 1998).
Table 2: Minimum detection limits of nutrients for project needs
For nutrient analysis are used kits (of 25 cells); in table 3 are presented the MERCK concentration kits for nutrient analysis. Portable refrigerators are used for the kits and samples to be kept in the right temperature, according to the exact specifications of the methodology.
Table 3: MERCΚ method and analysis kits
American Public Health Association (APHA). 1985. Standard methods for the examination of water and wastewater, 5210 Β. 5-Day BOD test, 16th edition. American Public Health Association, Washington DC.
American Public Health Association (APHA), American Water Works Association (AWWA), and Water Environment Federation (WEF). 1998. Standard Methods for the Examination of Water and Wastewater 20th Edition. United Book Press, Inc., Baltimore, Maryland.
